Zodiac MK6 engine

[Heino]

I recently purchase a Zodiac Mk6 HD boat and am in the process of restoring it.

Its a massive boat at 23" or 7m. Got an engine as well, a Yamaha 200 HP. Its a fairly old motor, a carbie 2 stroke. The leg is 25". Looking at the Zodiac specs, I note it should be a 20".

The motor is not fitted yet. Will it work or am I better off getting a shorter shaft.

Thanks in advance.

[office888]

Originally Posted by Heino

I recently purchase a Zodiac Mk6 HD boat and am in the process of restoring it.

Its a massive boat at 23" or 7m. Got an engine as well, a Yamaha 200 HP. Its a fairly old motor, a carbie 2 stroke. The leg is 25". Looking at the Zodiac specs, I note it should be a 20".

The motor is not fitted yet. Will it work or am I better off getting a shorter shaft.

Thanks in advance.

Some forewarning:

1. Trailer design is very important. the bunks must sufficiently support the tube, but the transom must be supported as well so that there is no strain on the tube connection when parked.
2. Whichever engine you choose, the cavitation plate should be approximately 25mm below the lowest point in the middle of the transom.
3. Proper inflation is EXTREMELY key. Underinflation will cause excessive flex, causing your boat to perform like total crap.
4. Remember at the end of the day that the boat is a SIB, so it will pound like crazy in rough seas. RIBs were invented in the late 60s to address that issue... The UK RNLI got tired of being fatigued from it.
5. They are very sensitive to load balance for proper planing. Put the load towards the stern, then transfer forward once it is on plane. Make sure to choose an engine within the weight capacity of the boat as well.

[Heino]

Thanks for your note.

I note there was a lengthy FC470 discussion on engine cavitation. You also note the cavitation plate should be approximately 25mm below the lowest point in the middle of the transom.

Does the hi-riders make any difference to the level of the engine mount. I want to make sure to motor does not lift out the water once on the plane.

Thanks

[office888]

Originally Posted by Heino

Thanks for your note.

I note there was a lengthy FC470 discussion on engine cavitation. You also note the cavitation plate should be approximately 25mm below the lowest point in the middle of the transom.

Does the hi-riders make any difference to the level of the engine mount. I want to make sure to motor does not lift out the water once on the plane.

Thanks

It's pretty much standard for all Futura-hull Zodiac boats.

The speed tubes will lift the boat out of the water substantially when on plane. The water line on these boats is just a little bit higher than where the material folds over on the bottom of the transom.

Your trim should be level, leaning towards a slight "bow up" attitude. The bow section of speed tube should juusstt barely be touching the water. The water spray should be coming off about 1/3 of the way back from the bow. section of the speed tube.

With heavier loads, the boat will have a tendency to dig the bow in more and your top speed will suffer, but the boat will still plane. Measured with GPS, depending on how much fuel I have left (I have a 12 gal tank on the bow thrustboard), my FC470 stays on plane until approximately 9 mph (10-11 mph with a full tank and two persons). I am running a non-standard lower unit though, so your results may vary.

[spartacus]

According to Zodiac MilPro website the recommended hp rating for the Zodiac is 115hp, although it can take up to a maximum of 175hp. The 200hp oil burner you've got will be an old-school Yammie V4 and will literally drink fuel.

More details here: http://zodiacmilpro.com/wp-content/u...or-Z801422.pdf

Like you say, these boats are massive and cost an arm and a leg new. You don't appreciate the size of them until you're up close and in my opinion are the big daddy of SIBs. I'm sure this one pictured is a MK V and it had a Yamaha 40hp on the back. You can see the speed tubes in the picture. It will have an HD aluminium interlocking deck, and the tube pressure is key to giving the whole boat rigidity.

If it were me I'd sell the Yammie and look for something in the 90-140hp. The Suzuki DF140 would be nice, with space for an auxiliary engine too.

[Heino]

On the engine size, the engine is on the upper range what you can add to the boat. The spec sheet note the max horsepower is 175 hp with 240 kg:

http://zodiacmilpro.com/wp-content/u...or-Z801422.pdf

The 200 hp is a little more powerful, but being a simple motor only weighs in at 210 kgs. I got it for a good price so will stomach the extra fuel use. I like the idea of the 6 cylinder sound and don't mind the smoke from the 2 stroke.

From my readings the older motors do use a lot more fuel at idle or trolling speeds, but at full blast only use around 10% more fuel compared to a 4 stroke.

So on the basis the transom will be OK with the weight I think its good to have the extra hp's on tap.

[office888]

Originally Posted by Heino

On the engine size, the engine is on the upper range what you can add to the boat. The spec sheet note the max horsepower is 175 hp with 240 kg:

http://zodiacmilpro.com/wp-content/u...or-Z801422.pdf

The 200 hp is a little more powerful, but being a simple motor only weighs in at 210 kgs. I got it for a good price so will stomach the extra fuel use. I like the idea of the 6 cylinder sound and don't mind the smoke from the 2 stroke.

From my readings the older motors do use a lot more fuel at idle or trolling speeds, but at full blast only use around 10% more fuel compared to a 4 stroke.

So on the basis the transom will be OK with the weight I think its good to have the extra hp's on tap.

An x-long shaft outboard (25") will not work on a longshaft (20") boat. Water will flow up the outboard leg in to the boat. The increased drag will negatively affect performance significantly.

You will need to change the leg to the 20" version or purchase a different outboard. I do not recommend raising the outboard, as it will act as a lever to increase stresses and potentially rip the transom off.

[prairie tuber]

Originally Posted by spartacus

I'm sure this one pictured is a MK V and it had a Yamaha 40hp on the back. You can see the speed tubes in the picture. It will have an HD aluminium interlocking deck, and the tube pressure is key to giving the whole boat rigidity.

That looks a bit small for a MK6, more like a MK4

Here is a video of a MK6 with a 235 evinrude 2 stroke

https://www.youtube.com/watch?v=y0opXamo2zk

[spartacus]

What's that shot on... 16mm film!

[Squid Boat]

Originally Posted by spartacus

What's that shot on... 16mm film!

16 is the bomb, thats look like consumer vhs 2nd gen, but I enjoyed watching it anyway.

Cheers

[prairie tuber]

I believe the video was done ~ 1980ish. It was made by a zodiac dealer local to where I used to live in Manitoba.

I was just made aware of this video last week by Projectile when he posted it in this thread:

http://www.rib.net/forum/f50/cav-pla...-53656-19.html